Methionine complexes

Reactions ofN-acetyl-L-Methionine Complexes ofPtu(en) with 5 -GMP and dGpG. Recently, intermolecular competition was studied in more de-... 

Thioethers form stable complexes, particularly if they are polydentate. Whereas only two sulfur atoms are coordinated in Ph2Pt(9S3),26 larger macrocycles, as in [Pt(12S4)]2+, can encapsulate the metal atom.27 The L-methionine complex (18-H-XII) is a metabolite of the anti-cancer drug cisplatin (see below).28... 

Although Samitz and Katz " found that methionine was capable of reducing chromate after 48 h at 37° (pH = 7) our studies of the reaction between methionine and chromate at pH 7.4 (1 M Tris HCl) showed no observable reaction at 25 °C. At 37 °C the reaction was extremely slow and certainly insignificant compared to cysteine. Chromium(III)-methionine complexes formed from reaction of chromium(III) with methionine contained coordinated -NH2 and -COO" groups but no Cr-S bonds. ... 

Frodl et al. [95] have incorporated the DNA intercalator dppz (dipyrido[3,2-a 2, 3 -c]phenazine) as a chelated diamine into [(ri -arene)Ru(Aa)(dppz)] (Aa = L-cysteine or i-methionine) complexes (e.g. 26, Fig. 2.17). Stable intercalative binding was observed with stability constants which increased from ca. 10 to ca. 10 as the charge on the complexes increased from +1 to +3. 

Mechanistic aspects of the action of folate-requiring enzymes involve one-carbon unit transfer at the oxidation level of formaldehyde, formate and methyl (78ACR314, 8OMI2I6OO) and are exemplified in pyrimidine and purine biosynthesis. A more complex mechanism has to be suggested for the methyl transfer from 5-methyl-THF (322) to homocysteine, since this transmethylation reaction is cobalamine-dependent to form methionine in E. coli. 

The body excretes platinum in various ways, mainly through urine the complex Pt(L-methionine-SN)2 is one of the few characterized products [206]. 

Methanol,, Y-methylimidazol-2-yldi(pyrid-2-yl)-. 2. ° metal complexes, 2, 89 Methanosarcina bryantii nickel, 6, 645 Methemerythrin, 4, 254 Methemocyanin. 6, 692 eopper(II) complexes, 5, 724 Methionine... 

In rheumatoid arthritis the damage that is found in joints may also be a result of the inactivation of a-1-PI due to the oxidation of an essential methionine(s) residue in this protein. It has been found that a-l-PI purified from the synovial fluid of patients with rheumatoid arthritis contained four Met(O) residues and was not able to form a binary complex with elastase89. It is probable that the presence of the Met(Oj residues in a-l-PI from these patients results from a high level of oxidants produced by neutrophils in the inflammed joint. 

McLafferty rearrangement 133, 163 Meisenheimer complexes 699, 702 Metal-chelated intermediates 838 Metal-halogen exchange 781, 784 Methionine, oxidation of 852-855 Methionine sulphone 853 Methionine sulphoxide 851-869 reduction of 1063 residues of... 

Enzymatic methylation of homocysteine (HSCHjCHjCHNHjCOOH) by methylcobalamin to give methionine (CH3SCH2CH2CHNH2COOH) was discovered in 1962 by Woods and co-workers, who also noticed the occurrence of a much slower, nonenzymatic reaction giving the same products. Methylcobinamide showed the same activity as the cobalamin in both the enzymatic and nonenzymatic reactions (72, 7/). It was subsequently discovered that HS, MeS , PhS , and w-BuS will dealkylate a variety of methyl complexes [DMG, DMG-BF2, DPG, G, salen, (DO)(DOH)pn, cobalamin] and even ethyl-Co(DMG)2 complexes to give the thioethers, and it was suggested that the reaction involved transfer of the carbonium ion to the attacking thiolate 161, 164), e.g.,... 

The first step in this process involves the binding of GTP by eIF-2. This binary complex then binds to met-tRNAf a tRNA specifically involved in binding to the initiation codon AUG. (There are two tRNAs for methionine. One specifies methionine for the initiator codon, the other for internal methionines. Each has a unique nucleotide sequence.) This ternary complex binds to the 40S ribosomal subunit to form the 43S preinitiation complex, which is stabilized by association with eIF-3 and elF-lA. 

Several cationic palladium(II) aqua complexes, [Pd(H20)4], cis-[PdL(H20)2] (L = en, methionine methyl ester, l,5-dithiacycloocta-3-ol), and [Pd(dien)(H20)], serve as the active catalyst for the selective hydration of various nitriles to the corresponding carboxamides, e.g., CHCI2CN was hydrated to CHCl2C(0)NH2 in the presence of... 

---